HVAC FOR SCHOOLS


Why humidity control belongs in the school HVAC conversation


Schools in the UK are under growing pressure to operate buildings that deliver consistent indoor environmental performance while working with ageing estates, constrained budgets, and increasingly demanding ventilation performance and monitoring requirements. Much of the focus has rightly centred on outdoor air rates and filtration, however, Stephen Finkel, DriSteem regional sales manager says one critical operational variable is often undervalued: relative humidity


M


aintaining appropriate indoor humidity is not simply a comfort consideration. Guidance on indoor environmental quality,


supported by international building science and public health research, shows that relative humidity directly influences how effectively school buildings perform, affecting system operation, occupant outcomes, and long-term building condition. As ventilation strategies evolve, humidity control should be addressed alongside ventilation and filtration as a core enabling condition for effective indoor air quality (IAQ) management, not as an optional add-on. During the heating season, when cold outdoor


air is continuously introduced and heated, school interiors are particularly prone to very low relative humidity. Cold outdoor air contains little moisture, and when it is heated without active humidity control, relative humidity drops sharply. In schools, this effect is intensified by high ventilation rates, large numbers of students and staff, and prolonged daily ventilation operation.


Protecting buildings as well as people


Sustained exposure to dry indoor conditions shifts the issue from a purely technical concern to one that affects daily building operation and occupant experience. Persistently low indoor humidity is associated with reduced respiratory protection, longer virus survival, and increased discomfort – including dry eyes, sore throats, and fatigue – particularly during winter months. Over time, this translates into higher absenteeism and increased IAQ complaints, placing additional strain on facilities teams and school leadership. Well-managed indoor environments support


effective learning. Research cited in UK guidance and international literature consistently links stable indoor environmental conditions to reduced absenteeism and improved academic performance. Respiratory illness remains one of the leading causes of missed school days; buildings that support immune defence help keep students and staff healthy, comfortable, and engaged. From a building operations perspective, relative


22 April 2026


humidity is a critical enabling condition. Maintaining appropriate humidity allows ventilation, heating, and filtration systems to operate as intended, supporting stable IAQ across varying occupancy levels and seasonal conditions. When humidity is not properly managed, even well- designed HVAC systems can struggle to maintain expected indoor conditions or deliver consistent performance. Humidity control also has direct implications for


asset protection and maintenance planning. Dry air can accelerate wear and damage to materials commonly found in schools, like books, musical instruments, wood finishes, flooring, classroom electronics, and IT equipment. In older or heritage school buildings, maintaining balanced relative humidity helps preserve original materials and finishes, reducing unplanned maintenance and extending their useful life.


Why advanced humidification matters


In high-ventilation school environments, how humidity is delivered and controlled is just as important as whether it is provided at all. Adding humidity to a school HVAC system is not simply a matter of introducing moisture; it must be added in a way that mixes quickly and evenly with the supply air and remains controllable under varying operating conditions.


Modern educational facilities increasingly rely on humidification systems integrated directly into airhandling units, designed to introduce moisture uniformly into the airstream before it is distributed throughout the building. Compared to older, room- based or local humidification approaches, centrally integrated humidification delivers several operational advantages that are particularly relevant in schools: ¡ Even distribution across classrooms, halls, and large communal spaces ¡ Rapid absorption, minimising the risk of condensation or wet surfaces


www.heatingandventilating.net


Left: Stephen Finkel, DriSteem regional sales manager


Above DriSteem’s RTS electric resistive humidifier is compatible with all water types and continuously learns as it runs, automatically adapting to optimise steam output and overall performance


Right: Ultra-sorb steam dispersion panels feature exceptionally short non-wetting distances, and their rapid, drip-free absorption ensures steam does not condense on downstream devices


¡ Compatibility with high outdoorair volumes common in education settings ¡ Precise control, allowing humidity to remain within recommended limits without over-humidification


Operational value for modern school estates


Building science and public health literature consistently identifies moderate indoor relative humidity, typically 40–60%, as supporting building performance and occupant well-being. From an operational standpoint, this range also aligns with stable HVAC operation, reduced fault conditions, and more predictable system behaviour. For UK schools, humidification should be viewed as a performance and assetmanagement tool, not an optional extra. Well-designed humidity control helps: ¡ Stabilise indoor environmental conditions across the year ¡ Reduce occupant complaints and reactive interventions ¡ Support the effective operation of ventilation and filtration investments ¡ Protect building materials, finishes, and electronic assets ¡ Lower unplanned maintenance demand over the life of the building As schools continue to modernise their estates and respond to rising expectations around indoor air quality, humidity control deserves a seat at the HVAC design table. It should be specified deliberately, delivered safely through advanced dispersion, and controlled with the same operational rigour applied to temperature and ventilation.


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